Massage is the manipulation of subject muscles and soft tissues in order to affect a release of tension. Massage involves many strategies, including kneading and stretching muscles, percussive striking, and vibration. Massage is well known in the fields of medicine, chiropractic, physical therapy, kinesiotherapy and fitness. Massage is practiced universally around the globe, both professionally and personally, and is recognized as providing some benefits to the mental, emotional and physical health of those receiving it.
In light of the almost universal appeal and recognition of massage, many different styles of massage have been developed, ranging from Shiatsu, Swedish, Deep Tissue, and others, and tools to aid in massage have developed in each discipline. One such tool is known as a massage roller or foam roller. Foam rollers are cylindrical or semi-cylindrical bodies made of a compliant material, such as foam, which are used for massaging and stretching soft tissues, increasing circulation, reducing pain, tension and stress from the soft tissues, improving posture and alignment, increase spinal mobility. Core and corrective exercises can be used with the roller as well.
Prior art solutions that use eccentric weights rotating about an axle fail to evenly distribute vibrations to a roller or other massager surface as they generally have only two contact points, one at the motor and one at or by a terminal end of the axle. This localizes all vibrational transmission at those two end points and can cause “weak spots” or “dead zones” along the length of a massager apparatus, especially if they are improperly spaced and allow destructive interference between the two points of contact. This spatial disparity in vibrational amplitude is a result of construction method with a motor and an eccentric weight mounted to a shaft extending from the motor to define a cylindrical axis. Stronger vibrations are created proximal to the weight with the vibrational amplitude decaying as a functional of lateral distance from the eccentric weight. As a result, when the weight is at one end of the roller, vibrations will dissipate inward from the weighted end along the length of the roller, whereas, a centrally located weight has vibrations that will still dissipate towards the ends. This vibrational amplitude decay is especially noticeable in longer rollers.
The use of several motors along a roller coupled to eccentric weights to alleviate these problems has met with limited success and also creates harmonic vibrating waves that tend to create points of low amplitude strength vibrations at certain positions along the roller with the position in part dictated by the rotational rate. Exemplary of these efforts is U.S. Pat. No. 6,647,572 in which vibratory nodes are partially mitigated and may be more evenly distributed, yet the reliance on several motors increases cost, weight, and device proclivity to breakage. The problems posed by motor failure are enhanced by the fact that the motor is generally inaccessible for repair and effectively encased in a surrounding roller material. Still another attempt to address the problem of vibrational amplitude inhomogeneity along the length of the roller involves mounting multiple eccentric weights along a single rotating shaft; however, this tends to either accentuate the inhomogeneity if the weights are radially aligned or if radially distributed around the shaft, torque is imparted to the motor that leads to motor damage. Moreover, mounting multiple eccentric weights along a single rotating shaft tends to cause increased imbalance of the roller, further exacerbating the problem of vibrational amplitude inhomogeneity and decreasing the overall therapeutic utility of the massage roller. A conventional method to compensate for wobble induced by eccentric weight rotation around a shaft has been to place housing contacting supports proximal to the shaft and rotating weight. The support also serves to transmit vibratory forces to the surface of the massager. Unfortunately, reliance on supports increases the complexity of forming the housing and also decreases the operational efficiency of the resultant massager.
Thus, there exists a need for a vibrating massage roller that provides a degree of positional uniformity in vibration along the roller imparted to a subject in contact with the roller with a simplified construction and operational efficiency to maximize the overall therapeutic utility to a subject in contact with the roller.